Concurrent Session II, Track A

1088: RWMWD Targeted Retrofit Program

Author(s): Paige Ahlborg, Ramsey-Washington Metro Watershed District; Marcy Bean, Barr Engineering

Description: In 2012, Ramsey-Washington Metro Watershed District (RWMWD) developed a Targeted Retrofit Program to help achieve water quality goals. In this program, technical assistance and grant funds are offered to select commercial, school, and faith-based properties in priority drainage areas or in under-served parts of RWMWD by developing partnerships to retrofit stormwater infrastructure to improve water quality. This has been facilitated by RWMWD through site assessment and tracking tools, partner development, planning and design, construction, ongoing maintenance, and signage and education.

In the decade since the program was created, over 40 properties have been retrofitted with a variety of best management practices (BMPs) at properties with high impervious surface coverage and no plans for future reconstruction that would trigger RWMWD’s stormwater permit requirements. Alongside District wide GIS mapping, TMDL tracking tools were developed to quantify the benefit of all capital projects and prioritize study areas. The Targeted Retrofit Program has helped RWMWD reduce pollutant loads in priority waterbodies and has led to long-standing partnerships. In this presentation, we will give an overview of the success of the Targeted Retrofit Program including details on site assessment and long-term maintenance and discuss how the program’s framework is being revisited to continue building relationships and prioritizing projects now that initial goals of the program have been met.

1068: Biochar as a Stormwater Filter Media Amendment: What's the Verdict?

Author(s): Justine Dauphinais, Coon Creek Watershed District; Chase Vanderbilt, Coon Creek Watershed District; Jon Janke, Coon Creek Watershed District; Ed Matthiesen, Stantec; Erik Megow, Stantec; Eileen Weigel, Stantec

Description: A silver bullet? Snake oil? A relatively low-cost, low-risk amendment with potential to improve filter performance? Based on three seasons of monitoring data from two large urban stormwater filters, we are leaning toward the latter. To date, we have observed a modest increase in E. coli removal compared to iron-sand media without added biochar and no significant difference in phosphorus removal or evidence of leaching. We will share performance monitoring results, design considerations, cost comparisons, and lessons learned from the two filters that have been operational since 2020 along with hot-off-the-press results from two additional regional biochar-iron-sand filters scheduled to be brought online in summer of 2023. Construction of the stormwater filters was supported by the MN Clean Water Fund, Cities of Blaine and Coon Rapids, and the Coon Creek Watershed District with design and engineering by Stantec.

1051: Standardizing Back-up Connections for Stormwater Reuse Irrigation to Lower Risk

Author(s): Laura Wehr, AE2S; Ben Guell, City of Woodbury; Kristin Seaman, City of Woodbury

Description: Stormwater reuse for irrigation is being used in Minnesota as an alternative BMP to meet volume control requirements for developments. This presentation will walk through how one community is setting standards for stormwater irrigation reuse systems that balance stormwater requirements and drinking water system protections. The overall goal of the presentation is to educate individuals on considerations for lowering risk to drinking water systems from reuse irrigation systems.

Stormwater reuse irrigation is often viewed as a win-win because it provides volume reduction for stormwater while reducing demand on drinking water. In Woodbury, infiltration prohibitions have led to stormwater reuse being installed. One issue with these systems is that rain does not always align with irrigation demand. Sole reliance on stormwater for irrigation can become challenging where there is a community expectation of green grass. To balance this, stormwater reuse systems often utilize a permanent backup connection to the City’s water system. When ponds run dry, irrigation is switched to drinking water. As the entity responsible for ensuring clean, safe drinking water to its residents, Woodbury staff are concerned about the contamination risk the direct connection between stormwater irrigation pipes and drinking water pipes creates. The City sought to standardize the use of backflow prevention methods in these systems to mitigate the risk without making the practice cost-prohibitive.

City staff from various departments worked together over the course of a year to understand their current reuse systems, identify the level of contamination risk of different designs, and create standards to increase protection of the drinking water system. The presentation will share findings from this work.

The work was completed at the beginning of 2023 and the first reuse systems to utilize the new standards are currently being installed. Results from the initial use of the standards will be included.

1111: Stormwater Treatment with a Manufacturing Byproduct

Author(s): John Gulliver, University of Minnesota; Rajneesh Singh, University of Minnesota

Description: Uncontrolled dumping of discarded tires is hazardous to our ecosystem, and disposal of tire waste to landfills is restricted. Consequently, their reuse in engineering fills as tire derived aggregates is gaining acceptance. During shredding of tires to manufacture tire derived aggregates (TDA), a waste byproduct is generated which has a high iron content. In preliminary batch studies, it was observed that the TDA byproducts can remove greater than 99% of the influent phosphorus concentration present in stormwater, but a leaching of zinc, copper and iron did occur. In this study, the role of biofilms in a TDA-based treatment system is investigated, in terms of phosphorous removal and potential leachability of different toxic metals. Synthetic stormwater and river water were applied as influent to different reactors containing TDA and TDA byproducts. To simulate multiple storms, influent applied to the reactors was flushed after every 72 hours and replaced with new influent. After 72 flushes, corresponding to roughly 6 years, it was observed that phosphorus removal capacity was higher in the reactors with biofilms, whereas, leachability of different metals was comparatively minimal in the reactors with biofilms. Reduced leachability and increased phosphorus removal could be attributed to the adsorption of leached metals and incorporation of phosphorus to biofilms. The result of this research is that, in laboratory pilot studies, the presence of biofilms makes the TDA waste product a viable stormwater treatment system for application in infiltration and underground storage chambers.

Concurrent Session II, Track B: Water and Agriculture: Cover Crops and Decision Support Tools

1010: Assessing the Environmental and Economic Impacts of Continuous Living Cover (CLC) Crops Over Time

Author(s): Trevor Russell, Friends of the Mississippi River; William Nielsen, Ecotone Analytics; Colin Cureton, University of Minnesota Forever Green Initiative; Mitch Hunter, University of Minnesota Forever Green Initiative; Peter LaFontaine, Friends of the Mississippi River

Description: "Continuous Living Cover" (CLC) cropping systems, including perennial and winter annual crops under development through the University of Minnesota Forever Green Initiative, show promise for improving water quality, soil health and habitat while diversifying and enhancing our agricultural economy.

Using a "wedge analysis" approach, this project forecasts the expected range of market growth for certain CLC cropping systems (perennial and winter annual crops) in Minnesota under a given time frame under "moderate" and "aggressive" adoption conditions.

This market assessment is paired with two complementary assessments: (1) An economic impact analysis that examines the potential on-farm economic impacts, paired with direct, indirect, and induced economic effects of each CLC adoption scenario; and (2) An environmental impact analysis that uses a statewide average coefficient-based environmental benefits assessment to examine the potential environmental impacts of each CLC adoption scenario.

This assessment provides a clear-eyed assessment of the long-term potential for CLC market demand and acreage and the likely range of economic and environmental outcomes of different adoption scenarios. The report is prepared in partnership between Friends of the Mississippi River, The Forever Green Partnership and Ecotone Analytics.

1006: Advancing Cover Crop Adoption – Advice from the Field

Author(s): Kimberly Musser, Water Resources Center, Minnesota State University, Mankato; Cammi Nordmeyer, Minnesota State University, Mankato; Tara O'Brien, Minnesota State University, Mankato

Description: Many conservation partners are working across the state to engage farmers and encourage soil health practice adoption. Currently, there is no resource available to help them understand what approaches have been successful in other parts of Minnesota. By aggregating and sharing advice for advancing cover crop adoption, anyone can learn directly from peers about proven tactics. The project goal is to collect advice from groups across the state who have successfully increased cover crop adoption in their region. Case study interviews will profile approaches with detailed, workable steps that can be taken to accelerate soil health practice adoption. Examples include advice for setting up and sustaining a soil health team, creating a county soil health demonstration farm, and supporting farmer led networks. Tips for increasing soil health practice adoption will be available for anyone interested such as conservation partners or soil health farmers leaders and mentors. This information will be available online, summarized in a case study booklet. The collective advice will help to improve information flow about workable tactics to inspire others to increase cover crop and conservation tillage practice adoption in their area.

1009: Cover Crops and Living Mulches Effects on Irrigated Corn-Soybean Production Systems: An Integral Management Strategy for Sandy Soils

Author(s): Eduardo Garay Lagos, University of Minnesota; Fabian Fernandez, University of Minnesota; Rodney Venterea, University of Minnesota; Julie Grossman, University of Minnesota; Vasudha Sharma, University of Minnesota; Jake Kastenbauer, University of Minnesota

Description: The state of Minnesota, USA has over 240,000 ha of irrigated glacial outwash sands that are predominantly under corn and soybean cultivation. While highly productive and important to Minnesota’s economy, these soils are highly vulnerable to nitrogen (N) losses. While farmers are encouraged to go beyond traditional production approaches by implementing sustainable cultural practices, such as cover cropping, there is limited research aiming to holistically understand the effect of cover crops on N cycling (N availability, nitrate leaching, nitrous oxide emissions and ammonia volatilization) and competition with corn and soybean for resources under irrigated conditions. This study was established in 2011 in an irrigated sandy loam soil at Westport, Minnesota. Three adjacent blocks of continuous corn (CC), corn-soybean (CSb) and soybean-corn (SbC) cropping systems were used. Treatments included N fertilizer rates of 0, 100, 200, 250 and 300 kg N ha-1 split-applied at V2, V6, and V10 development stages of the CC and CSb while no N was applied in the SbC. Each N rate had winter-rye (Secale cereale) and winter fallow. Kura clover (Trifolium ambiguum M. Bieb.) living mulch was present in the 0, 200 (CSb only) and 250 (CC only) kg N ha-1 rates. Cover crops did not differ in terms of biomass accumulation across N rates, although the CSb cropping system resulted in higher cover crop biomass and N content. Kura clover reduced nitrate loading by 60% compared to the other treatments across rotations and N rates. However, Kura clover tended to result in a yield penalty in corn cropping systems. Results from this study will also include a comprehensive N budget assessment which will provide an improved strategy in nutrient and water management for sandy soils to optimize agronomic production while substantially minimizing agricultural environmental impact.

1002: DAWN (Dashboard for Agricultural Water Use and Nutrient Management): Taking Farm Decisions to a New Level Through Smart Predictions

Author(s): Melissa Kenney, University of Minnesota, Institute on the Environment (IonE); Elizabeth Abraham, University of Minnesota, Institute on the Environment; Ashley Peters, University of Minnesota, Institute on the Environment

Description: Farm decisions such as crop choice, fertilizer use, and irrigation scheduling have wide ranging impacts on water availability and quality, cascading far beyond individual farms and watersheds. Single-point decision-support tools that exclude interactions across systems, regions, or sectors may provide misleading information and cause inefficient outcomes. Through the Dashboard for Agricultural Water Use and Nutrient Management (DAWN) project, researchers, and developers have created predictive decision support tools to sustain food and energy crop production in the Corn Belt. The DAWN project, supported by a USDA NIFA grant, launched its first agricultural decision support tools: the Crop Progress Tool and the Growing Degree Day (GDD) tool in spring 2023. Tools around irrigation, nutrient management, crop yield, and finance models are in development. The tool dashboard provides credible, usable, and predictive information for agricultural producers and water managers to improve land, water, and fertilizer use synergies across multiple systems and scales. We are currently gathering expert feedback through surveys, user stories, and think-alouds to support scoping the tools under development and evaluating the usability of the tools that are already launched.

Our talk will feature information about DAWN and stakeholder engagement to improve usability, a breakdown of DAWN’s predictive technology and why it is an improvement over current decision support tools, and the results of initial user testing.

Concurrent Session II, Track C

1042: St. Louis River Watershed Mercury Total Maximum Daily Load Analysis

Author(s): Madeline Keefer, Tetra Tech; Jon Butcher, Tetra Tech; Afshin Shabani, Tetra Tech; Michelle Schmidt, Indigo Agriculture

Description: In 2007 the Minnesota Pollution Control Agency (MPCA) issued statewide mercury (Hg) Total Maximum Daily Loads (TMDLs). These addressed over 75 percent of the state’s waterbodies listed as impaired for elevated mercury in water and fish tissue, with Hg sources primarily from atmospheric deposition. However, MPCA also found that the statewide reductions were not sufficient for waters with fish tissue levels exceeding 0.572 mg-THg/kg due to local conditions that result in higher fish tissue or total Hg concentrations. These exceptions apply to the St. Louis and Cloquet River watersheds, where multiple segments are impaired for fish tissue (53) and water column (22) mercury criteria excursions. This watershed has high densities of carbon-rich wetlands and peatlands that provide loci for Hg methylation, as well as sulfate sources associated with mining. While sulfate and dissolved organic carbon (DOC) concentrations are both important for Hg methylation, Hg concentrations here are not well correlated with sulfate loads; instead, they correlate with DOC, likely as an index of transport from wetlands and uplands to streams. We used established HSPF models of the watersheds to simulate DOC as a surrogate for both total and methyl Hg transport for pervious lands plus atmospheric deposition of Hg to impervious surfaces and streams and a bioaccumulation factor approach to fish tissue concentration to evaluate site-specific load reduction targets. Model development for this project will be completed in 2024.

1038: Statewide PFAS Testing Initiative at the Minnesota Department of Health

Author(s): Jane de Lambert, MDH; Steve Robertson, Minnesota Department of Health

Description: The Minnesota Department of Health (MDH) has recently completed sampling nearly all community water systems (CWSs) in Minnesota for PFAS (per- and poly- fluoroalkyl substances). The main objectives of this effort were to evaluate whether Minnesotans are exposed to PFAS in drinking water at levels above health-based guidance values and to assess occurrence of PFAS in drinking water across the state.

MDH has completed this goal through several monitoring projects, including the Statewide PFAS Testing Initiative. MDH has sampled over 900 community water systems between 2020 and 2023 with the help of contractors. Sample collection was completed in March 2023. All samples were analyzed using EPA Method 533.

The first round of sampling at CWSs targeted those that are most vulnerable to PFAS contamination to address the highest potential public health risks. MDH selected systems for participation based on nearby sources or detections of PFAS, population served and geologic vulnerability. Subsequent sampling rounds were broader in scope, including CWSs that are not considered at high risk for PFAS exposure. An interactive PFAS Dashboard on the MDH website displays the results for all systems, after they have been shared with participating CWSs. Current data indicate that PFAS are detected in roughly 40 percent of systems sampled, with PFBA most commonly detected. Threshold values relative to health-based guidance are rarely exceeded (less than one percent of CWSs). Results will be provided in the context of Minnesota health-based guidance values as well as the new proposed MCLs from the Environmental Protection Agency (EPA).

1109: Introducing the Low Salt, No Salt Minnesota Program

Author(s): Jessica Wilson, City of Edina; Liz Forbes, Riley Purgatory Bluff Creek Watershed District

Description: Overuse of de-icers for winter maintenance is a growing problem in Minnesota lakes, ponds, wetlands, streams, and groundwater. The leading source of chloride pollution is from deicing chemicals (salts) used for winter maintenance. The leading strategy for managing chloride pollution is to be smart about its use: applying it only when, where, and in the amount needed. While progress has been made in the public sector, the private sector continues to overuse salt, despite access to training and knowledge of best practices.

The Hennepin County Chloride Initiative (HCCI), a collaborative of watersheds, cities, agencies, and volunteers, developed the Low Salt, No Salt Minnesota program to address over-salting on private properties. Our research revealed that the biggest driver of over-salting in the private sector is client demand due to fear of slip-and-fall lawsuits.

The team worked closely with a Minnesota marketing firm to establish a brand, interview target audiences, identify key messages, and develop engagement materials. This program leverages awareness and technical support to help people identify custom solutions that suit specific needs of residents, businesses, and property managers and empowers them to act. The ability to maintain safety while realizing financial savings and improving sustainability are key messages conveyed through this program.

The Low Salt, No Salt program provides a toolbox for Local Government Units (LGUs) to build community capacity to maintain winter safety while reducing chloride-based deicer use. The program officially launched with its inaugural train-the-trainer session in January 2023.

1040: Hold the Salt: A GIS Tool to Help Winter Maintenance Salt Reduction

Author(s): Mark Gallagher, SRF Consulting Group; Rick Lovel, SRF Consulting Group

Description: Sodium chloride (salt) is an effective and commonly used roadway anti-icing compound. Salt lowers the melting point of water and allows dangerous ice build up to be prevented or more effectively removed. However, increasing salt concentrations in roadway-adjacent soils and waters can have significant detrimental affects on habitats, flora, and fauna.

The Clear Roads Consortium is an association of 38 states the conducts research and develops guidelines for winter maintenance, including anti-icing operations. To address the undesired effects of salt applications, Clear Roads conducted a research and development project to create Geographic Information System (GIS) tools to identify the areas near roadways that are most sensitive to salt exposure. Once identified, alternative methods to solid salt applications that minimize the transport and build-up of salt in the environment can be employed.

Working with SRF Consulting group, an initial review of the impacts of salt exposure, mechanisms of salt transport from the roadway, and effects of distance from the roadway was conducted. This review was then used to create a model of the interaction of salt with the local environment and create and create a high-resolution scoring system for areas near the roadway. The GIS tool produces maps of high, medium, and low sensitivity areas along snow plowing routes. With this data, managers can consider reducing salt application, switching to brine pretreatment or other methods to reduce salt exposure.

Concurrent Session II, Track D: Flood Resiliency Planning and Implementation

1030: Davenport’s Flood Resiliency Plan

Author(s): Teresa Stadelmann, HR Green, Inc.

Description: The City of Davenport offers unparalleled access, views, and connectivity with the Mississippi River along much of its nine-mile riverfront. Living with and working alongside the river has shaped the City’s three-pronged approach to reduce flood risk through retreat, mitigation, and active flood fighting. In 2019, the city experienced record flooding when the Mississippi River exceeded flood stage for 103 days and reached a new record crest. The 2019 flood event galvanized public support to reassess the City’s approach to mitigating flood risk. Beginning in August 2020, the City embarked on a year-long planning study to develop recommendations to improve, simplify, and enhance the City’s response to Mississippi River floods, resulting in the Davenport Flood Resiliency Plan.

The presentation will discuss the City’s planning process including three waves of public and stakeholder engagement opportunities; building consensus around the themes of resilience, operations, equity, and public access; and developing concepts and recommendations for structural and nonstructural flood mitigation, operational efficiencies, and transportation improvements. The balance of nonstructural and structural recommendations within the Plan is challenging and intentional: that tension reflects the acute differences in public opinion regarding flood risk, financial investment in flood mitigation efforts, level of service, accessibility, and viewsheds. The Plan offers short-term, incremental solutions and over the long-term, transitions the City’s three-pronged approach away from flood fighting and toward structural and nonstructural mitigation solutions, while balancing respect for and retreat from the river.

1080: Future Development Stormwater Planning? How to Plan For Growth in a Community Rapidly Developing from Rural to Urban

Author(s): Tony Miller, AE2S; Luke LaMoore, AE2S

Description: This presentation will walk through how one community is planning for rapid greenfield development over the next few decades. The overall goal of the presentation is to better educate individuals on how to develop an understanding of how water flows/ponds within the one’s study area as well as how to plan for future stormwater infrastructure needs. Otsego is a rapidly growing community. The City had been using a HydroCAD model, that was originally created in the early 2000s, for planning and designing stormwater infrastructure. However, this HydroCAD model needed an update to account for new developments and updated Atlas-14 rainfall. In addition, Otsego Creek has preliminary FEMA flood mapping. Unfortunately, the preliminary mapping was created using far less detailed hydraulic data than what the City has. If these maps were to ever become effective, the regulatory floodplain would be based on inferior hydraulic data and the HydroCAD model (not being an approved FEMA software) would not be sufficient in applying for FEMA map amendments/revisions.

This led the City to develop two new XPSWMM models of the watershed. One of these models is an existing 100-year model. This model gives the City a strong understanding of the current flood inundation areas. It also provides the City with a FEMA-approved model in the event that future FEMA map amendments/revisions should be needed. The second of these models is a “full build” model. This model attempts to simulate the watershed once it is fully developed. This allows the City to plan for future infrastructure, both for land acquisition/timing as well as properly funding the watershed’s stormwater fund.

The City and their consultant have worked together over the course of a year to understand the stormwater system, identify any challenges, and develop a strong 20-year stormwater infrastructure plan.

1081: Morningside Flood Infrastructure Project – Diving Into a New Era of Stormwater Management Projects

Author(s): Marcy Bean, Barr Engineering; Sarah Stratton, Barr Engineering

Description: Reducing flood risk in established urban spaces is challenging. There is limited public space for new infrastructure, and existing public infrastructure is becoming undersized or obsolete due to climate change.

The City of Edina’s Morningside Flood Infrastructure Project (Project) was the first flood risk reduction project implemented after development of the City’s Flood Risk Reduction strategy. The Project started with inundation mapping from storm events, and two-dimensional modeling capturing overland flow routing, to develop a deeper understanding of the neighborhood’s flood risk. With this baseline in place, design options iteratively balanced tradeoffs in cost, effectiveness, land use, resident input, and impacts.

Final design incorporated innovative flood management solutions (Adaptive Level Control System, or predictive pumping), neighborhood-scale storm sewer pipe improvements and expansion, collaboration with transportation projects, permitting challenges, impacts to a local woodland, and integration with a highly valued and utilized existing city park. While flood risk reduction drove the project, a multidisciplinary team collaborated with the City to support their natural resources goals, and creatively wove together a complex flood infrastructure project with park improvements, enhancing habitat and providing water quality improvement.

Construction of the $12M+ Project started in 2022. Infrastructure construction, as well as native habitat restoration and planting of over 1, 200 trees will round out the completion of the project in summer 2023. We will present how the project evolved our understanding of flood risk and how multi-disciplinary teams and willing City partners conceived and implemented an innovative project to serve the neighborhood for years to come.

1031: Strategies for Managing a Stormwater Utility

Author(s): Ross Bintner, City of Edina

Description: The City of Edina owns a stormwater utility with assets valued at $110M (current replacement value) and generates > $6M/yr for capital expenditures and operations. This presentation will describe key strategies that the managers of the Edina stormwater utility use to manage, define, maintain and grow the services of the utility, as well describe our approach to the key trends and challenges of aging infrastructure and climate adaptation.